<template>
  <div class="xtx-carousel">
    <ul class="carousel-body">
      <li
        class="carousel-item"
        v-for="(item, key) in banner"
        :key="item.id"
        :class="{ fade: key == index }"
        @mouseenter="changeInterval(true)"
        @mouseleave="changeInterval(false)"
      >
        <RouterLink to="/">
          <!-- v-show="index == key"  -->
          <img :src="item.imgUrl" />
        </RouterLink>
      </li>
    </ul>
    <a href="javascript:;" class="carousel-btn prev" @click="clickIcon('up')"
      ><i class="iconfont icon-angle-left"></i
    ></a>
    <a href="javascript:;" class="carousel-btn next" @click="clickIcon('down')"
      ><i class="iconfont icon-angle-right"></i
    ></a>
    <div class="carousel-indicator">
      <span
        @click="changeImg(key)"
        v-for="(i, key) in banner.length"
        :key="i.id"
        :class="key === index ? 'active' : ''"
      ></span>
    </div>
  </div>
</template>

<script>
import { getBanner } from "@/utils/api/headerapi";
export default {
  data() {
    return {
      index: 0, //所在图的下标
      timer: null, //时间为空
      banner: [], //对象
    };
  },
  mounted() {
    this.getBanner();
    this.setInterval();
  },
  methods: {
    //渲染数据
    async getBanner() {
      let res = await getBanner();
      this.banner = res.result;
    },
    //开启定时器
    setInterval() {
      // 事件里定时器应该先清除在设置，防止多次点击直接生成多个定时器
      clearInterval(this.timer);
      this.timer = setInterval(() => {
        this.index++;
        if (this.index > this.banner.length - 1) {
          this.index = 0;
        }
      }, 2000);
    },
    // 点击控制圆点
    changeImg(index) {
      this.index = index;
    },
    //轮播的图片
    changeInterval(val) {
      if (val) {
        clearInterval(this.timer);
      } else {
        this.setInterval();
      }
    },
    //点击切换
    clickIcon(val) {
      if (val === "down") {
        this.index++;
        if (this.index === this.banner.length) {
          this.index = 0;
        }
      } else {
        /* 第一种写法
					this.index--;
					if(this.index < 0){
						this.index = this.banner.length-1;
					} */
        // 第二种写法
        if (this.index === 0) {
          this.index = this.banner.length;
        }
        this.index--;
      }
    },
  },
};
</script>

<style lang="scss" >
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 270px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
.active {
  background-color: rgb(255, 255, 255) !important;
}
</style>